Imidazoquinazoline compounds are known to have an inhibitory activity on blood platelet agglutination and an inhibitory activity on metastasis of cancers as described in U.S. Pat. Nos. 4,596,806 and 4,610,987, and Japanese Patent Application (OPI) Nos. 4186/85 and 152416/85 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application").
Clin. Exp. Immunol., Vol. 61, 388-396 (1985) describes a relation between blood platelets and nephritis of acute serum sickness and protection of nephritis by dipyridamole [2,6-bis(diethanolamino)-4,8-dipiperidinopyrimido[5,4,-d]pyrimidine, Merk Index 10th Ed.] as a coronary vasodilator of FUT-175 [2-(6-amino)naphthyl 4-guanidinobenzoate dihydrochloride] as a Clr and Cl esterase inhibitor, but does not refer to effectiveness of imidazoquinazolines according to this invention as an agent for treatment and prevention of nephritis.